Evolution of the shark

                    

                            sharks date back  450-420 million years before land and plants all shark came from the type of shark called megalodon and the shark megalodon was 67 feet long and still lives to this day and eats whales and other sharks . sharks grow 10 to 1000 teeth over a life time modern sharks look and think more different thain the sharks of the past.

cladoselache shark only found in the devonian period 370 million yaers ago a fast swimmers and at a size of 6 feet long 

teeth of the cladoselache shark 

 Helicoprion shark

 (Dmitri Bogdanov)

                                                   

                                                              crested horn shark





this shark has two dorsal fins they are both spines they are bottom duelers and and are nocturnal and eat off the reefs and all of the small organisms they prefer rocky vegetated areas they swim down (305)ft or (90)meters down and they can not harm humans and you can see the two horns on the head that gave them there name and they hide there eggs in sea weed and the crested horn baby is 22 cm long 

     in my idea of the sharks life style the shark would be a good pet

                                                              leopard shark
the leopard shark got is name for its spots the leopard shark can be in silver and brown and is a small shark for a while they can grow up to 4.3 feet long and has slender like body they are fond around mexico north america and they like tropical waters and are found in groups and they eat small fish or small crabs and other small things. the leopard sharks are harmless to humans and are traded for food and the aquariums. the leopard shark has been used for large tanks and are grate to swim with and swim 13 feet down and are safe from grate whites and other big sharks      in my words this shark is a small size

                                                                              blue shark

                                  

         this shark can blend in with the the blue sea and are hard  to see and they are fast, they like tropical waters and swim down 350 feet down in the ocean, about 10 to 20 million of this shark are killed and by fishing nets, the skin is used for leather and the fins and meat is used for shark fin soup and other meals and the leather can be used for oil, some of the predators are the tiger shark the grate whites and killer whiles, they eat cuttlefish lobster octopus shrimp and crab.

                                                                Hammerhead shark

the hammerhead shark are a shark that that is in a groups they are a part of the sphyrnidae they have a hammer like head  this shark moves in packs and they are like a eel the use electric signals from  fish in the water the size scale is up to 13 to 20 feet long.

                                                                                6 gill shark 

Skin color ranges from tan to brown to black. It has a light colored lateral line down the sides and on the fins' edges. There are darker colored spots on the sides. The general shape is a heavy, powerful body that has a broad head with small eyes. The pupils are black and the eye color is a fluorescent blue green. The blunt nose six gill shark can grow to 4.8 m (16 ft). Adult males generally average between 3.1–3.3 m (10–11 ft), while adult females average, The blunt nose six gill shark is a member of the Hexanchidae family. Many of its relatives areextinct - there are more closely related relatives in the fossil record than there are living species. The living species that are closest genetically include the dogfish, the Greenland shark, as well as other six- and sevengilled sharks. Some of the shark's relatives date back to 200 million years ago. This shark is a notable species due to both its primitive and current physical characteristics. what I think is the 6 gill can swim th down deep

                                                                           The bull shark


       the bull shark is a salt or fresh water shark it is aggressive they travel far up rivers the bull shark has the bull and grate white have the same similarities in bite marks, the bull shark swims up rivers and attack. bull sharks will hunt in pairs of two they get their name by their the depth they are mostly found at the death of 150meters but dos not go no more than 30meters, they travel up the Mississippi river although their have ben less fresh water attacks they are responsible for near shore shark attacks my opinion is the bull shark is the worlds scent deadliest shark other than the grate white

                                                                        the tiger shark
                    
                        

                                     the tiger shark another name for it is the sea tiger the tiger shark is mostly a nocturnal hunter its diet includes crab, fish, seals, birds, squid ,turtles, sea snakes,The tiger shark can grow up to (16)ft long and like tropical waters.they have been known to attack humans and can disappear in the water and they are not likely to swim away after biting a human.    

disappearing tiger shark

                                                             grate whighte shark
         
The mighty grate white shark it has a pointed snout and it is a man eating shark it is a large shark the length
     of the shark is 20ft,the life span of over 30 years the weight is up to(5,000lb) the shark reaches maturity around the age 15 the great white is one of the worlds largest predators in the sea.